1. Field of the Invention
The present invention relates to an electronic component and a method of manufacturing the same and more particularly, the present invention relates to electronic components such as high-frequency composite modules used for communications and other uses, and constructed so as to accommodate surface-mounting components inside a shielding case, and a method of manufacturing the same.
2. Description of the Related Art
As an electronic component, for example, as is shown in FIG. 17, there is an electronic component 60 with a shielding case which is constructed such that a surface-mounting component 64 is accommodated inside a shielding case 65 by inserting engagement protrusion portions 66 of the shielding case 65 into concave engagement portions 62 on the inside surface of a printed-circuit board 61. The inside surface of the printed-circuit board 61 has fixing-electrodes (not illustrated) disposed thereon and the surface-mounting component 64 is mounted on the printed-circuit board 61 by fixing the engagement protrusion portions of the shielding case 65 to the fixing-electrodes by solder 67.
In a conventional manufacturing method for an electronic component having a shielding case, soldering paste for mounting components is printed on an aggregate printed-circuit board (mother printed-circuit board) along a large area which is to be divided into a plurality of electronic components, a plurality of surface-mounting components are placed on the mother printed-circuit board, reflow soldering is performed and the surface-mounting components are mounted, then the mother printed-circuit board is divided into individual elements, and then a shielding case is soldered to each of the divided individual elements.
In another method in which through-holes are formed in a mother printed-circuit board, a plurality of surface-mounting components are placed on the mother printed-circuit board, then the through-holes are completely filled with soldering paste, engagement protrusion portions with which each of a plurality of shielding cases is provided are inserted into the through-holes and assembled, the plurality of shielding cases are fixed on the mother printed-circuit board by reflow soldering, and then the mother printed-circuit board is divided into individual electronic components.
However, in the first method described above, since a shielding case is mounted on each of the divided printed-circuit boards, there is a problem of poor production efficiency.
Furthermore, with respect to the second method described above, since soldering paste is generally applied to the engagement holes such that the engagement holes are completely filled with the soldering paste, when the mother printed-circuit board is cut and divided into a plurality of electronic components, the mother printed-circuit board and the solder in the through-holes are cut in the same plane, and accordingly burrs of the solder are produced on the back of the mother printed-circuit board and the solderability at the time of mounting is impaired, dicing cutters are clogged with solder and their life span is shortened, or solder chips produced by dicing stick to products and as a result, the characteristics of the products are decreased.
Furthermore, if the engagement holes are completely filled with solder (soldering paste), the fixing of engagement protrusion portions (for example, nail-like portions) to case-fixing electrodes in the engagement holes cannot be visually confirmed and the reliability is deteriorated, the usage of solder increases and the weight of products is increased, when the condition connected with feeding of soldering paste such as the diameter of engagement holes, the thickness of printed-circuit boards, etc., is changed, adjustments for stabilizing the feeding quantity of soldering paste are required and as a result, there is a problem of reducing productivity.
In order to overcome the problems described above, preferred embodiments of the present invention provide a method of manufacturing an electronic component by which an electronic component having a construction in which surface-mounting components are accommodated inside a shielding case are efficiently manufactured and electronic components having very high reliability are efficiently manufactured by such a manufacturing method.
In a preferred embodiment of the present invention, a method of method an electronic component having a construction in which surface-mounting components are accommodated inside a shielding case, includes the steps of preparing a mother printed-circuit board on which a plurality of surface-mounting components are to be mounted, the mother printed-circuit board having component-connecting electrodes to which external electrodes of the surface-mounting components are to be connected, engagement holes into which engagement protrusion portions of a shielding case are to be inserted, and case-fixing electrodes provided inside the engagement holes, mounting a plurality of surface-mounting components on the mother printed-circuit board, and connecting external electrodes of the surface-mounting components to the component-connecting electrodes of the mother printed-circuit board, applying soldering paste in the vicinity of the engagement holes on the mother printed-circuit board or in an area covering a portion of the engagement hole and in the vicinity of the engagement holes from the side of the component-mounted surface on which the surface-mounting components have been mounted, such that soldering paste is not entirely filled inside the engagement hole, engaging a plurality of shielding cases with the mother printed-circuit board such that the engagement protrusion portions of the shielding case are inserted into the engagement holes of the mother printed-circuit board, soldering the engagement protrusion portions of the shielding cases to the case-fixing electrodes inside the engagement holes by melting the soldering paste, and then cutting the mother printed-circuit board into areas on each of which a shielding case is mounted and dividing the mother printed-circuit board into a plurality of individual electronic components in each of which surface-mounting components are accommodated inside a shielding case.
With the unique method described in the previous paragraph, it becomes possible to manufacture an electronic component having a construction in which surface-mounting components are accommodated inside a shielding case by mounting a plurality of surface-mounting components on a mother printed-circuit board provided with component-connecting electrodes, engagement holes into which engagement protrusion portions of a shielding case are inserted, and case-fixing electrodes provided inside the engagement holes, connecting external electrodes to the component-connecting electrodes, then applying soldering paste in the vicinity of the engagement holes on the mother printed-circuit board or in an area covering a portion of the engagement hole and the vicinity of the engagement holes from the side of the component-mounted surface such that soldering paste is not entirely filled in the engagement holes, making a plurality of shielding cases engaged in the mother printed-circuit board, then soldering the engagement protrusion portions of the shielding cases to case-fixing electrodes inside the engagement holes by melting solder in the soldering paste, and then cutting the mother printed-circuit board and dividing the mother printed-circuit board into separate electronic components.
That is, since the shielding cases are mounted in the stage of a mother printed-circuit board, production efficiency is greatly improved when compared with the case in which the shielding cases are mounted on each of divided printed-circuit boards.
Furthermore, since the engagement holes are not completely filled with soldering paste, the advantages described in the following paragraphs are achieves.
Since the engagement holes are not entirely filled with solder (soldering paste), when the mother printed-circuit board is cut into areas on each of which a shielding case is mounted and divided into a plurality of individual electronic components, the mother printed-circuit board and the solder inside the through-holes are not cut in the same plane. As a result, burrs of solder are not formed on the back of the printed-circuit boards and thus, the solderability at the time of mounting of products is not deteriorated.
When the mother printed-circuit board is cut by dicing cutters, the cutters can be prevented from being clogged with solder, and the lifespan of the cutters is prevented from being shortened.
Solder chips produced by dicing do not stick to products and thus, excellent characteristics of the products are achieved.
The usage of solder is reduced and it becomes possible to make the weight of products lighter.
Even if the condition related to feeding of soldering paste such as the diameter of engagement holes, the thickness of printed-circuit boards, and other characteristics, is changed, adjustments for stabilizing the feeding quantity of soldering paste are not required and increased productivity is achieved.
Since the engagement holes in printed-circuit boards are not entirely filled with solder (soldering paste), it becomes possible to visually confirm the fixing of engagement protrusion portions (for example, nail-like protrusions) to case-fixing electrodes in the engagement holes.
Moreover, in preferred embodiments of the present invention, the statement that soldering paste is applied such that soldering paste is not entirely filled in the engagement holes is a concept meaning that soldering paste is supplied so that soldering paste does not substantially fill the main portion of engagement holes, and the entrance of a small quantity of soldering paste into engagement holes is not excluded.
Furthermore, according to another preferred embodiment of the present invention, a method of manufacturing an electronic component having a construction in which surface-mounting components are accommodated inside a shielding case, includes the steps of preparing a mother printed-circuit board on which a plurality of surface-mounting components are to be mounted, the mother printed-circuit board provided with component-connecting electrodes to which external electrodes of the surface-mounting components are to be connected, engagement holes into which engagement protrusion portions of a shielding case are to be inserted, and case-fixing electrodes provided inside the engagement holes, mounting a portion of a predetermined number of surface-mounting components on the mother printed-circuit board and connecting external electrodes of the surface-mounting components to the component-connecting electrodes of the mother printed-circuit board, applying soldering paste to component-connecting electrodes on which surface-mounting components are not mounted yet, and applying soldering paste in the vicinity of the engagement holes or in an area covering a portion of the engagement hole and the vicinity of the engagement holes on the mother printed-circuit board, from the side of the component-mounted surface on which the surface-mounting components have been mounted, such that soldering paste is not entirely filled inside the engagement hole, placing the surface-mounting components which are not mounted yet on the mother printed-circuit board such that the external electrodes of the surface-mounting components not mounted yet are opposed to the soldering paste applied on the component-connecting electrodes, engaging a plurality of shielding cases-with the mother printed-circuit board such that the engagement protrusion portions of shielding cases are inserted into the engagement holes of the mother printed-circuit board, soldering the external electrodes of the surface-mounting components put on the mother printed-circuit board later to the component-connecting electrodes and soldering the engagement protrusion portions of the shielding cases to case-fixing electrodes inside the engagement holes by melting the soldering paste, and then cutting the mother printed-circuit board into areas on each of which a shielding case is mounted and dividing the mother printed-circuit board into a plurality of individual electronic components in each of which surface-mounting components are accommodated inside a shielding case.
With the unique method of manufacturing described in the preceding paragraph, the same advantages achieved by the manufacturing method for an electronic component according to the above-described first preferred embodiment of the present invention is achieved, and since the mounting process of surface-mounting components is separated into two, other processes can be performed between the two mounting processes and accordingly the freedom of the manufacturing processes is greatly improved.
Furthermore, in another preferred embodiment of a method of manufacturing an electronic component of the present invention, a land electrode to be electrically connected to a shielding case is provided in the vicinity of an engagement hole on the component-mounted surface of the mother printed-circuit board and a portion of the shielding case and the land electrode are constructed so as to be connected to each other preferably via soldering.
By providing a land electrode to be electrically connected to a shielding case in the vicinity of a engagement hole on the component-mounted surface of a printed-circuit board and by connecting a portion of the shielding case to the land electrode preferably via soldering, it becomes possible to increase the reliability of electrical connection, and accordingly it becomes possible to make the present invention even more effective.
That is, since the engagement protrusion portions of a shielding case are fixed to the case-fixing electrodes inside engagement holes of a printed-circuit board, the mechanical connection of the shielding case to the printed-circuit board is securely and reliably achieved, and since the shielding case is connected to the land electrode through soldering, the electrical connection between the shielding case and the printed-circuit board is securely and reliably achieved. Accordingly, it becomes possible to increase the reliability of both mechanical and electrical connection and as a result, the reliability as a whole is greatly improved.
In an electronic component according to another preferred embodiment of the present invention, surface-mounting components are soldered to component-connecting electrodes on a printed-circuit board and a shielding case that is provided to accommodate surface-mounting components is soldered to case-fixing electrodes provided on the internal surface of concave portions on the side of the printed-circuit board by a very small quantity of solder that occupies a portion inside of the concave portion.
An electronic component according to another preferred embodiment of the present invention is manufactured by a manufacturing method for an electronic component according other preferred embodiments of the present invention, and since a shielding case is securely fixed to a case-fixing electrode provided in a printed-circuit board, very high reliability is achieved. Furthermore, it is possible to efficiently manufacture this electronic component via the above-described preferred embodiments of the manufacturing method of the present invention.
Other features, characteristics, elements and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments thereof with reference to the attached drawings.